Legacy or colonization? Posteruption establishment of peregrine falcons (Falco peregrinus) on a volcanically active subarctic island.

How populations and communities reassemble following disturbances are affected by a number of factors, with the arrival order of founding populations often having a profound influence on later populations and community structure. Kasatochi Island is a small volcano located in the central Aleutian archipelago that erupted violently August 8, 2008, sterilizing the island of avian biodiversity. Prior to the eruption, Kasatochi was the center of abundance for breeding seabirds in the central Aleutian Islands and supported several breeding pairs of peregrine falcons (Falco peregrinus). We examined the reestablishment of peregrine falcons on Kasatochi by evaluating the genetic relatedness among legacy samples collected in 2006 to those collected posteruption and to other falcons breeding along the archipelago. No genotypes found in posteruption samples were identical to genotypes collected from pre-eruption samples. However, genetic analyses suggest that individuals closely related to peregrine falcons occupying pre-eruption Kasatochi returned following the eruption and successfully fledged young; thus, a genetic legacy of pre-eruption falcons was present on posteruption Kasatochi Island. We hypothesize that the rapid reestablishment of peregrine falcons on Kasatochi was likely facilitated by behavioral characteristics of peregrine falcons breeding in the Aleutian Islands, such as year-round residency and breeding site fidelity, the presence of an abundant food source (seabirds), and limited vegetation requirements by seabirds and falcons.

Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea.

Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea.

Taxonomic and Conservation Status of the Yuma Mountain Lion.

Confusion persists over the taxonomic status and viability of the Yuma mountain lion (Felis concolor browni). We conducted a review of the literature on lions in the American Southwest and interviewed resource and public-land managers and wildlife researchers to help us understand the current status of the Yuma mountain lion. We also contacted museums and assembled the most complete set of morphometric data on the Yuma mountain lion. Few if any breeding female lions, a paucity of prey, and a lack of suitable habitat within the reported range of this population cast doubt on its status. We conclude that subspecific status is probably not warranted. El estado taxoómico y de conservación del león de las Montañas Yuma.

Resumen: Persiste cierta confusión acerca del estado taxonómico y la viabilidad del león de las Montañas Yuma (Felis concolor browni). En el presente trabajo, realizamos una revisión de la literatura sobre lesones en el Sudoeste de los Estados Unidos y entrevistamos a encargados del manejo de la tierra e investigadores de vida silvestre para ayudarnos a comprender el actual estado del León de las Montañas Yuma. También contactamos museos y construímos el conjunto de datos morfoméricos más completo sobre el León de las Montañas Yuma. La ausencia casi absoluta de hembras reproductoras, la escasez de presas y la falta de hábitat adecuado dentro del área de distribución concida de esta población pone en duda su estado. Concluímos que probablemente, el estatus de subespecie no esta justificado.